Timing of imbrication of an active continental margin facing the northern branch of Neotethys, Kargı Massif, northern Turkey

Abstract

The Kirazbaşı Complex, in the Kargı Massif in the Pontides, is a mixture of ophiolitic and deep-marine sedimentary rocks and blocks of different origins. In the northern part of the massif, where these rocks are imbricated with pre-Cretaceous metamorphic units, it displays an ordered stratigraphy and has a siliciclastic-dominant nature. This part was deposited in piggy-back and thrust-top basins during the Turonian to Campanian. In the southern part, the Kirazbaşı Complex is dominantly represented by deep-marine sediments, such as distal turbidites and cherts, and ophiolitic and epi-ophiolitic rocks, representing foredeep sediments and accretionary wedges. Two sections measured from foredeep deposits of the Kirazbaşı Complex in this area yielded rich radiolarian faunas, both from the matrix and from the blocks. Based on these radiolarian faunas, Late Valanginian to Early Barremian and Middle Albian to latest Cenomanian ages are assigned to those deposits forming the matrix of the Kirazbaşı Complex. Rich radiolarian faunas from an alternating chert-mudstone block within this matrix reveals a latest Bajocian to Early Callovian age. According to our results, the Neotethys Ocean reached an oceanic stage before the Late Bajocian, and was consumed by northward subduction during the Valanginian to Campanian.